diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5c0fc64
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+bazel*
\ No newline at end of file
diff --git a/BUILD b/BUILD
new file mode 100644
index 0000000..e69de29
diff --git a/WORKSPACE b/WORKSPACE
new file mode 100644
index 0000000..d80f088
--- /dev/null
+++ b/WORKSPACE
@@ -0,0 +1,9 @@
+workspace(name = "io_bazel_rules_prometheus")
+
+load(":deps.bzl", "prometheus_repositories")
+
+prometheus_repositories()
+
+register_toolchains(
+    "//prometheus/toolchain:all",
+)
diff --git a/deps.bzl b/deps.bzl
new file mode 100644
index 0000000..234ef59
--- /dev/null
+++ b/deps.bzl
@@ -0,0 +1,15 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+PROMETHEUS_VERSION = "2.23.0"
+PROMETHEUS_DARWIN_ARCH = "darwin-amd64"
+PROMETHEUS_DARWIN = "{PROMETHEUS_VERSION}.{PROMETHEUS_DARWIN_ARCH}"
+PROMETHEUS_DARWIN_URL = "https://github.com/prometheus/prometheus/releases/download/v{PROMETHEUS_VERSION}/prometheus-{PROMETHEUS_VERSION}.{PROMETHEUS_DARWIN_ARCH}.tar.gz"
+
+def prometheus_repositories():
+    http_archive(
+        name = "prometheus_darwin",
+        sha256 = "d589a45495cea1aa74bff82335d2145f2d93b8b357c3398739b9139c74dc0cfe",
+        urls = [PROMETHEUS_DARWIN_URL],
+        strip_prefix = "prometheus-%s.%s" % (PROMETHEUS_VERSION, PROMETHEUS_DARWIN_ARCH),
+        build_file = "@//:prometheus.BUILD",
+    )
diff --git a/examples/BUILD b/examples/BUILD
new file mode 100644
index 0000000..fe334e0
--- /dev/null
+++ b/examples/BUILD
@@ -0,0 +1,59 @@
+load("//prometheus:prometheus.bzl", "promtool_config_test", "promtool_unit_test")
+
+promtool_unit_test(
+    name = "test_rules_yml",
+    srcs = [
+        "tests.yml",
+    ],
+    rules = ["rules.yml"],
+)
+
+promtool_unit_test(
+    name = "test_rules_json",
+    srcs = [
+        "tests.json",
+    ],
+    rules = ["rules.json"],
+)
+
+promtool_unit_test(
+    name = "test_rules_multiple",
+    srcs = [
+        "tests.json",
+        "tests.yml",
+    ],
+    rules = [
+        "rules.json",
+        "rules.yml",
+    ],
+)
+
+promtool_config_test(
+    name = "test_config_yml",
+    srcs = ["prometheus.yml"],
+)
+
+promtool_config_test(
+    name = "test_config_json",
+    srcs = ["prometheus.json"],
+)
+
+promtool_config_test(
+    name = "test_config_multiple",
+    srcs = [
+        "prometheus.json",
+        "prometheus.yml",
+    ],
+)
+
+test_suite(
+    name = "all_tests",
+    tests = [
+        ":test_config_json",
+        ":test_config_multiple",
+        ":test_config_yml",
+        ":test_rules_json",
+        ":test_rules_multiple",
+        ":test_rules_yml",
+    ],
+)
diff --git a/examples/prometheus.json b/examples/prometheus.json
new file mode 100644
index 0000000..b97103a
--- /dev/null
+++ b/examples/prometheus.json
@@ -0,0 +1,28 @@
+{
+  "global": {
+    "scrape_interval": "15s",
+    "evaluation_interval": "15s"
+  },
+  "alerting": {
+    "alertmanagers": [
+      {
+        "static_configs": [
+          {
+            "targets": null
+          }
+        ]
+      }
+    ]
+  },
+  "rule_files": null,
+  "scrape_configs": [
+    {
+      "job_name": "prometheus",
+      "static_configs": [
+        {
+          "targets": ["localhost:9090"]
+        }
+      ]
+    }
+  ]
+}
diff --git a/examples/prometheus.yml b/examples/prometheus.yml
new file mode 100644
index 0000000..312b578
--- /dev/null
+++ b/examples/prometheus.yml
@@ -0,0 +1,29 @@
+# my global config
+global:
+  scrape_interval: 15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
+  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
+  # scrape_timeout is set to the global default (10s).
+
+# Alertmanager configuration
+alerting:
+  alertmanagers:
+    - static_configs:
+        - targets:
+          # - alertmanager:9093
+
+# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
+rule_files:
+  # - "first_rules.yml"
+  # - "second_rules.yml"
+
+# A scrape configuration containing exactly one endpoint to scrape:
+# Here it's Prometheus itself.
+scrape_configs:
+  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
+  - job_name: "prometheus"
+
+    # metrics_path defaults to '/metrics'
+    # scheme defaults to 'http'.
+
+    static_configs:
+      - targets: ["localhost:9090"]
diff --git a/examples/rules.json b/examples/rules.json
new file mode 100644
index 0000000..dee0bb3
--- /dev/null
+++ b/examples/rules.json
@@ -0,0 +1,33 @@
+{
+  "groups": [
+    {
+      "name": "example",
+      "rules": [
+        {
+          "alert": "InstanceDown",
+          "expr": "up == 0",
+          "for": "5m",
+          "labels": {
+            "severity": "page"
+          },
+          "annotations": {
+            "summary": "Instance {{ $labels.instance }} down",
+            "description": "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
+          }
+        },
+        {
+          "alert": "AnotherInstanceDown",
+          "expr": "up == 0",
+          "for": "10m",
+          "labels": {
+            "severity": "page"
+          },
+          "annotations": {
+            "summary": "Instance {{ $labels.instance }} down",
+            "description": "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
+          }
+        }
+      ]
+    }
+  ]
+}
diff --git a/examples/rules.yml b/examples/rules.yml
new file mode 100644
index 0000000..895ccaa
--- /dev/null
+++ b/examples/rules.yml
@@ -0,0 +1,22 @@
+# This is the rules file.
+
+groups:
+  - name: example
+    rules:
+      - alert: InstanceDown
+        expr: up == 0
+        for: 5m
+        labels:
+          severity: page
+        annotations:
+          summary: "Instance {{ $labels.instance }} down"
+          description: "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
+
+      - alert: AnotherInstanceDown
+        expr: up == 0
+        for: 10m
+        labels:
+          severity: page
+        annotations:
+          summary: "Instance {{ $labels.instance }} down"
+          description: "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
diff --git a/examples/tests.json b/examples/tests.json
new file mode 100644
index 0000000..257b292
--- /dev/null
+++ b/examples/tests.json
@@ -0,0 +1,62 @@
+{
+  "rule_files": ["rules.json"],
+  "evaluation_interval": "1m",
+  "tests": [
+    {
+      "interval": "1m",
+      "input_series": [
+        {
+          "series": "up{job=\"prometheus\", instance=\"localhost:9090\"}",
+          "values": "0 0 0 0 0 0 0 0 0 0 0 0 0 0 0"
+        },
+        {
+          "series": "up{job=\"node_exporter\", instance=\"localhost:9100\"}",
+          "values": "1+0x6 0 0 0 0 0 0 0 0"
+        },
+        {
+          "series": "go_goroutines{job=\"prometheus\", instance=\"localhost:9090\"}",
+          "values": "10+10x2 30+20x5"
+        },
+        {
+          "series": "go_goroutines{job=\"node_exporter\", instance=\"localhost:9100\"}",
+          "values": "10+10x7 10+30x4"
+        }
+      ],
+      "alert_rule_test": [
+        {
+          "eval_time": "10m",
+          "alertname": "InstanceDown",
+          "exp_alerts": [
+            {
+              "exp_labels": {
+                "severity": "page",
+                "instance": "localhost:9090",
+                "job": "prometheus"
+              },
+              "exp_annotations": {
+                "summary": "Instance localhost:9090 down",
+                "description": "localhost:9090 of job prometheus has been down for more than 5 minutes."
+              }
+            }
+          ]
+        }
+      ],
+      "promql_expr_test": [
+        {
+          "expr": "go_goroutines > 5",
+          "eval_time": "4m",
+          "exp_samples": [
+            {
+              "labels": "go_goroutines{job=\"prometheus\",instance=\"localhost:9090\"}",
+              "value": 50
+            },
+            {
+              "labels": "go_goroutines{job=\"node_exporter\",instance=\"localhost:9100\"}",
+              "value": 50
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
diff --git a/examples/tests.yml b/examples/tests.yml
new file mode 100644
index 0000000..6b5b028
--- /dev/null
+++ b/examples/tests.yml
@@ -0,0 +1,48 @@
+# This is the main input for unit testing.
+# Only this file is passed as command line argument.
+
+rule_files:
+  - rules.yml
+
+evaluation_interval: 1m
+
+tests:
+  # Test 1.
+  - interval: 1m
+    # Series data.
+    input_series:
+      - series: 'up{job="prometheus", instance="localhost:9090"}'
+        values: "0 0 0 0 0 0 0 0 0 0 0 0 0 0 0"
+      - series: 'up{job="node_exporter", instance="localhost:9100"}'
+        values: "1+0x6 0 0 0 0 0 0 0 0" # 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
+      - series: 'go_goroutines{job="prometheus", instance="localhost:9090"}'
+        values: "10+10x2 30+20x5" # 10 20 30 30 50 70 90 110 130
+      - series: 'go_goroutines{job="node_exporter", instance="localhost:9100"}'
+        values: "10+10x7 10+30x4" # 10 20 30 40 50 60 70 80 10 40 70 100 130
+
+    # Unit test for alerting rules.
+    alert_rule_test:
+      # Unit test 1.
+      - eval_time: 10m
+        alertname: InstanceDown
+        exp_alerts:
+          # Alert 1.
+          - exp_labels:
+              severity: page
+              instance: localhost:9090
+              job: prometheus
+            exp_annotations:
+              summary: "Instance localhost:9090 down"
+              description: "localhost:9090 of job prometheus has been down for more than 5 minutes."
+    # Unit tests for promql expressions.
+    promql_expr_test:
+      # Unit test 1.
+      - expr: go_goroutines > 5
+        eval_time: 4m
+        exp_samples:
+          # Sample 1.
+          - labels: 'go_goroutines{job="prometheus",instance="localhost:9090"}'
+            value: 50
+          # Sample 2.
+          - labels: 'go_goroutines{job="node_exporter",instance="localhost:9100"}'
+            value: 50
diff --git a/prometheus.BUILD b/prometheus.BUILD
new file mode 100644
index 0000000..6b1a1b8
--- /dev/null
+++ b/prometheus.BUILD
@@ -0,0 +1,4 @@
+exports_files([
+    "prometheus",
+    "promtool",
+])
diff --git a/prometheus/BUILD b/prometheus/BUILD
new file mode 100644
index 0000000..ffd0fb0
--- /dev/null
+++ b/prometheus/BUILD
@@ -0,0 +1 @@
+package(default_visibility = ["//visibility:public"])
diff --git a/prometheus/internal/BUILD b/prometheus/internal/BUILD
new file mode 100644
index 0000000..331ddf1
--- /dev/null
+++ b/prometheus/internal/BUILD
@@ -0,0 +1,12 @@
+package(
+    default_visibility = ["//prometheus:__subpackages__"],
+)
+
+exports_files(
+    glob([
+        "*.bat",
+        "*.sh",
+        "*.sh.tpl",
+    ]),
+    visibility = ["//visibility:public"],
+)
diff --git a/prometheus/internal/promtool.bzl b/prometheus/internal/promtool.bzl
new file mode 100644
index 0000000..7e43606
--- /dev/null
+++ b/prometheus/internal/promtool.bzl
@@ -0,0 +1,75 @@
+def _promtool_unit_test_impl(ctx):
+    """promtool_unit_test implementation: we spawn test runner task from template and provide required tools and actions from toolchain"""
+
+    # To ensure the files needed by the script are available, we put them in
+    # the runfiles.
+    promtool_info = ctx.toolchains["//prometheus/toolchain:toolchain_type"].prometheusToolchainInfo.promtool
+    promtool_unit_test_runner_template = promtool_info.template.files.to_list()[0]
+
+    runfiles = ctx.runfiles(
+        files = ctx.files.srcs + ctx.files.rules,
+        transitive_files = promtool_info.tool.files,
+    )
+
+    test = ctx.actions.declare_file("%s.out.sh" % ctx.label.name)
+
+    ctx.actions.expand_template(
+        template = promtool_unit_test_runner_template,
+        output = test,
+        is_executable = True,
+        substitutions = {
+            "%srcs%": " ".join([_file.short_path for _file in ctx.files.srcs]),
+            "%tool_path%": "%s" % promtool_info.tool.files_to_run.executable.short_path,
+            "%action%": ctx.attr._action,
+        },
+    )
+    return [DefaultInfo(runfiles = runfiles, executable = test)]
+
+promtool_unit_test = rule(
+    implementation = _promtool_unit_test_impl,
+    test = True,
+    attrs = {
+        "_action": attr.string(default = "test rules"),
+        "srcs": attr.label_list(mandatory = True, allow_files = True, cfg = "target"),
+        "rules": attr.label_list(mandatory = True, allow_files = True),
+    },
+    toolchains = ["//prometheus/toolchain:toolchain_type"],
+)
+
+def _promtool_config_test_impl(ctx):
+    """promtool_unit_test implementation: we spawn executor task from template and provide required tools"""
+
+    # To ensure the files needed by the script are available, we put them in
+    # the runfiles.
+
+    promtool_info = ctx.toolchains["//prometheus/toolchain:toolchain_type"].prometheusToolchainInfo.promtool
+    promtool_unit_test_runner_template = promtool_info.template.files.to_list()[0]
+
+    runfiles = ctx.runfiles(
+        files = ctx.files.srcs,
+        transitive_files = promtool_info.tool.files,
+    )
+
+    test = ctx.actions.declare_file("%s.out.sh" % ctx.label.name)
+
+    ctx.actions.expand_template(
+        template = promtool_unit_test_runner_template,
+        output = test,
+        is_executable = True,
+        substitutions = {
+            "%srcs%": " ".join([_file.short_path for _file in ctx.files.srcs]),
+            "%tool_path%": "%s" % promtool_info.tool.files_to_run.executable.short_path,
+            "%action%": ctx.attr._action,
+        },
+    )
+    return [DefaultInfo(runfiles = runfiles, executable = test)]
+
+promtool_config_test = rule(
+    implementation = _promtool_config_test_impl,
+    test = True,
+    attrs = {
+        "_action": attr.string(default = "check config"),
+        "srcs": attr.label_list(mandatory = True, allow_files = True),
+    },
+    toolchains = ["//prometheus/toolchain:toolchain_type"],
+)
diff --git a/prometheus/internal/promtool.sh.tpl b/prometheus/internal/promtool.sh.tpl
new file mode 100755
index 0000000..8fa7316
--- /dev/null
+++ b/prometheus/internal/promtool.sh.tpl
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+set -e
+
+%tool_path% %action% %srcs%
diff --git a/prometheus/internal/providers.bzl b/prometheus/internal/providers.bzl
new file mode 100644
index 0000000..3bd3937
--- /dev/null
+++ b/prometheus/internal/providers.bzl
@@ -0,0 +1,8 @@
+PromtoolInfo = provider(fields = {
+    "tool": "Promtool label",
+    "template": "Template script that will be filled with execution details",
+})
+
+PrometheusInfo = provider(fields = {
+    "tool": "Prometheus label",
+})
diff --git a/prometheus/prometheus.bzl b/prometheus/prometheus.bzl
new file mode 100644
index 0000000..6fb89de
--- /dev/null
+++ b/prometheus/prometheus.bzl
@@ -0,0 +1,11 @@
+load(
+    "//prometheus/internal:promtool.bzl",
+    _promtool_unit_test = "promtool_unit_test",
+)
+load(
+    "//prometheus/internal:promtool.bzl",
+    _promtool_config_test = "promtool_config_test",
+)
+
+promtool_unit_test = _promtool_unit_test
+promtool_config_test = _promtool_config_test
diff --git a/prometheus/toolchain/BUILD b/prometheus/toolchain/BUILD
new file mode 100644
index 0000000..848ca0e
--- /dev/null
+++ b/prometheus/toolchain/BUILD
@@ -0,0 +1,28 @@
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+load(":toolchain.bzl", "prometheus_toolchain")
+
+toolchain_type(name = "toolchain_type")
+
+prometheus_toolchain(
+    name = "prometheus_darwin",
+    prometheus = "@prometheus_darwin//:prometheus",
+    promtool = "@prometheus_darwin//:promtool",
+    promtool_executor_template = "//prometheus/internal:promtool.sh.tpl",
+)
+
+toolchain(
+    name = "prometheus_toolchain_darwin",
+    exec_compatible_with = [
+        "@platforms//os:osx",
+        "@platforms//cpu:x86_64",
+    ],
+    target_compatible_with = [
+        "@platforms//os:osx",
+        "@platforms//cpu:x86_64",
+    ],
+    toolchain = ":prometheus_darwin",
+    toolchain_type = ":toolchain_type",
+)
diff --git a/prometheus/toolchain/toolchain.bzl b/prometheus/toolchain/toolchain.bzl
new file mode 100644
index 0000000..def514c
--- /dev/null
+++ b/prometheus/toolchain/toolchain.bzl
@@ -0,0 +1,36 @@
+load("//prometheus/internal:providers.bzl", "PrometheusInfo", "PromtoolInfo")
+
+PrometheusToolchainInfo = provider(fields = [
+    "name",
+    "prometheus",
+    "promtool",
+])
+
+# genrule to work with real machine instead of sandboxed bazel environment?
+
+def _prometheus_toolchain_impl(ctx):
+    toolchain_info = platform_common.ToolchainInfo(
+        prometheusToolchainInfo = PrometheusToolchainInfo(
+            name = ctx.label.name,
+            prometheus = PrometheusInfo(
+                tool = ctx.attr.prometheus,
+            ),
+            promtool = PromtoolInfo(
+                tool = ctx.attr.promtool,
+                template = ctx.attr.promtool_executor_template,
+            ),
+        ),
+    )
+    return [
+        toolchain_info,
+    ]
+
+prometheus_toolchain = rule(
+    implementation = _prometheus_toolchain_impl,
+    attrs = {
+        "prometheus": attr.label(mandatory = True, allow_single_file = True, executable = True, cfg = "exec"),
+        "promtool": attr.label(mandatory = True, allow_single_file = True, executable = True, cfg = "exec"),
+        "promtool_executor_template": attr.label(mandatory = True, allow_single_file = True),
+    },
+    provides = [platform_common.ToolchainInfo],
+)